I wanted to make a custom based on Prime Breakdown but I cannot think of any figures that would make a good base, Armored Trucks seem to be very rare among Transformers.
Not really fond of Animated's design but I can see that if I wanted to do that they have Swindle and Soundwave that would work so for any Animated and Prime fans there you go. I think Hasbro may need to make more Armored trucks that's just too good of an alt mode to not use more often.
Movie Ratchet would be my first choice. Sure, it would require some work to make it look more Prime-sy, though.